Heat-exchangers

ABSTRACT

868,348. Tubular heat exchangers. SVENSKA FLAKTFABRIKEN A. B. Oct. 6, 1959 [Jan. 28, 1959], No. 33834/59, Class 64(3) In a heat exchanger comprising a bank of pipe coils 2 arranged within a casing 1 through which air is caused to flow and wherein each coil consists of a number of tubes 3 interconnected in series by bends 4 located outside the casing, bleed pipes 8 interconnect certain of the bends 4 and this arrangement is said to prevent freezing up and consequent bursting of the tubes, when for example the air is being heated, by permitting the heating fluid to pass between relatively warm and cold zones of the tube bank. The pipes 8 may interconnect tube bends at the air entry end of the pipe or, as indicated at 8&lt;SP&gt;1&lt;/SP&gt; may interconnect other tube bends in the bank. Each tube bend may consist of two tube parts interconnected by a member adapted also to receive the end of a pipe 8 or 8&lt;SP&gt;1&lt;/SP&gt;.

B. PELLMYR HEAT-EXCHANGERS April 3, 1962 Filed Oct. 8, 1959 FIG. 2

mvcm'on: BENGT PELLMYR ATTYS.

United States Patent 3,828,149 Patented Apr. 3, 1962 fine 3,028,149 HEAT-EXCHANGERS Bengt Pellmyr, Jonkoping, Sweden, assignor to Aktiebolaget Svenska Fliiktiabriken, Stockholm, Sweden Filed Oct. 8, 1959, Ser. No. 845,171 Claims priority, application Sweden Jan. 28, 1959 4 Claims. (Cl. 257-448) The present invention relates to a device for heatexchaugcrs for exchange of heat between a flowing medium and air, which consists of a number of pipe-coils enclosed in a casing or a channel for the gaseous medium, each coil comprising a number of tubes coupled in series, mutually connected with pipe-bends located outside the casing. In heat-exchangers especially of the counter current types there exists during water use the danger of bursting due to freezing of the fluid contained in the inner tubes when it is used for heating outside air. Usually the tubes directly in contact with the outside air and especially if the tubes are finned-are subjected to the heaviest cooling effect, for which reason the congelation starts here in the tubes with the consequence that the circulation of the fiuid medium, which is in the pipe-bend located outside the cover, will be stopped. At continued freezing this medium will be expanded and thereby cause bursting of the pipe-bends of the tubes.

The invention, by simple means prevents bursting of such heat-exchangers, since the heat exchanger is furnished with one or more narrow equalization pipes connecting the pipe-bends located outside the casing in one part of the heat-exchanger-preferably in the part of the heat-exchanger, which is closest to the air-inlet-either mutually or with pipe-bends in another part of the heatexchanger.

Equalization pipes may suitably be connected with the pipe-bends by means of special fittings, made to simultaneously serve as necessary joint-elements between the tubes working in series.

The invention will now be described in more detail with reference to the accompanying drawing, which shows an exemplifying embodiment of an arrangement according to the invention and wherein FIG. 1 shows a perspective view of a heat-exchanger made in accordance with the invention and FIG. 2 shows a detail of a pipe-bend provided with a special fitting.

In the drawing 1 indicates a casing or channel through which air is flowing from A to B. 2 indicates a number of pipe-coils enclosed in the cover 1, each comprising a number of tubes 3 coupled in series. These are mutually connected with pipe-bends 4, located outside the casing 1. 5 indicates a supply pipe for the flowing medium for instance hot water and 6 indicates an outlet-pipe for the mentioned medium. The tubes are furnished with fins, which in the drawing are indicated as 7. In accordance with the invention the heat-exchanger is furnished with one or more narrow equalization pipes 8, in the present case connecting the pipe-bends located outside the casing 1, in that part of the heat-exchanger, which is closest to the air-intake A. The equalization pipes may also connect the mentioned pipe-bends with pipe-bends in another part of the heat-exchanger, as in the drawing indicated with 8. By using equalization pipes of a small dimension, the medium is for the most exposed parts of the heat-exchanger when risk of freezing is at hand transferred to parts located outside the zone of freezing risk without jeopardizing the normal flow in series through the heat-exchanger. 9 indicates special fittings, which are made to serve simultaneously as necessary joint-elements between the tubes working in series. In this case the tubes proper are bent to outside the casing, The bent parts of the tubes are indicated as 4a and 4b respectively.

What I claim is:

1. In a heat exchanger for exchange of heat between a flowing heat exchange medium and air, a casing having an air inlet and an air outlet and forming a channel for the air, a plurality of pipe coils each comprising a number of tubes disposed within said casing and connected in series by pipe bends positioned outside the casing, and at least one small pipe of smaller cross section than said coils disposed outside the casing and connected to separae pipe bends in the part of the heat exchanger which is closest to the air inlet exterior of said casing to transfer the medium in one of said bends to the other of said bends and prevent bursting of the tubes adjacent the air inlet in the event of freezing during the operation of the heat exchanger, the small pipe affording the transfer of medium between said bends without jeopardizing the normal flow in series through the tubes of each coil.

2. A heat exchanger according to claim 1 wherein the tubes of each pipe coil are disposed in a plane parallel to the flow of air through said channel, said small pipe interconnecting the pipe bends of all of the coils immediately adjacent said air inlet.

3. A heat exchanger according to claim 1 wherein the tubes of each pipe coil are disposed in a plane parallel to the flow of air through said channel, said small pipe connecting the pipe bend of one coil immediately adjacent said air inlet with the bend of said coil next adjacent said air inlet.

4. A heat exchanger according to claim 1 wherein said pipe bends comprise integral parts of adjacent tubes bent at right angles to said tubes exterior of said casing and a. fitting interconnecting said parts to afford unrestricted flow therebetween, said small pipe being connected to said fitting to communicate with said bend therethrough.

References Qited in the file of this patent UNITED STATES PATENTS 194,856 Young Sept. 4, 1877 825,828 Haskins July 10, 1906 1,134,518 Day Apr. 6, 1915 1,908,733 Creel May 16, 1933 2,301,433 McElgin Nov. 10, 1942 2,693,679 Staebler Nov. 9, 1954 2,896,429 Karmazin July 28, 1959 2,954,213 Pellegrini Sept. 27, 1960 

